import org.omg.CORBA.TRANSACTION_MODE;

import java.util.LinkedList;

public class No068 {
    public class TreeNode {
        int val;
        TreeNode left;
        TreeNode right;

        TreeNode(int x) {
            val = x;
        }
    }

    /**
     * 给定一个二叉树, 找到该树中两个指定节点的最近公共祖先。
     */
    public TreeNode lowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q) {
        if(root == null || root == p || root == q) {
            return root;
        }
        TreeNode left = lowestCommonAncestor(root.left, p, q);
        TreeNode right = lowestCommonAncestor(root.right, p, q);
        if(left == null)
            return right;

        if(right == null)
            return left;
        return root;
    }

    /**
     * 给定一个二叉搜索树, 找到该树中两个指定节点的最近公共祖先。
     */
    public TreeNode lowestCommonAncestor2(TreeNode root, TreeNode p, TreeNode q) {
        if (root.val > p.val && root.val > q.val) return lowestCommonAncestor(root.left, p, q);
        if (root.val < p.val && root.val < q.val) return lowestCommonAncestor(root.right, p, q);
        return root;
    }
}
